Note: Descriptions are shown in the official language in which they were submitted.
1 336~01
HEATING APPARATUS
This invention relates to heating apparatus,
particularly of the type which makes use of heat from
existing heating or cooking apparatus.
Open fires, closed fires, boilers, cookers (solid fuel,
oil or gas), ceiling mounted radiant gas heaters and etc,
loose valuable heat to the outside atmosphere without the
benefit of all the heat generated having contributed to the
inside atmosphere of the home or workplace.
Heat is transmitted by three means; Radiation,
Convection and Conduction. Most of the heat transmitted to
the room from an open fire is by radiation. No convected
heat emits from an open fire - it cannot. All the convected
heat and most of the conducted heat - which conducted heat in
turn transfers to convected heat in the main as air passing
over the fire surrounds draws on that heat and takes it away
up the flue - is lost up the flue and in turn to the outside
atmosphere.
All fires - unless supplied with air for combustion in a
sealed ducted source from the exterior - actually lower room
temperature for some time after starting up. An open fire on
an exterior wall is at best 10% efficient, on an interior
wall is at best 20% efficient. A free standing closed solid
fuel fire is at best 30% efficient. Solid fuel, oil or gas
cookers are at best 53% efficient. Ceiling mounted radiant
gas heaters are at best 30~ efficient; and wall mounted
radiant/convector gas heaters are at best 50% efficient.
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Solid fuel, oil or gas boilers are in the 50% - 60%
efficiency range with the most efficient being a very low
output gas boiler in the region of 74% efficiency. These
figures take into account all the heat generated which
actually finds its way first to the interior including that
which bleeds through the linings and structure of the flue to
the interior. The remaining percentage is the heat energy
which is lost to the outside atmosphere without benefit to
the purpose for the heating system - this is the heat lost up
the flue in the form of the convected heat generated in the
system, and in turn a part of that convected heat which is
converted to conducted heat and lost through the exterior
lining and structure of the flue.
An object of this invention is to provide apparatus
which makes use of the otherwise wasted heat and put it back
to the interior of the area being heated.
According to the present invention, there is provided
heating apparatus for heating an environment, comprising a
passage defining a flow path for warm gas, the flow path
being adapted to pass warm gas past a plurality of heat
exchange tubes generally transverse to the flow path and
spaced therealong, the tubes forming at least in part at
least one heat exchange conduit adapted to carry air through
the flow path from a downstream to an upstream part thereof
indirect heat exchange, and air-flow inducing means for
inducing a flow or air in the or each conduit and thence to
the said environment, characterized in that the spacing
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between adjacent tubes progressively decreases in the
downstream direction of the flow path thereby in use
progressively improving the rate of heat exchange between the
air and the warm gas.
Preferably said one or more heat exchange conduits
comprises one or more first banks of parallel tubes ext~n~ing
into a said heat flow path, the inlets of said tubes being
operatively connected to said air flow-inducing means, and
one or more second banks of parallel tubes connected directly
or indirectly to the outlets of said first tubes and
extending out of said heat flow path.
Preferably said one or more heat exchange conduits
comprises a plurality of parallel tube elements which provide
a sinuous flow path for air.
Preferably the or each heat exchange conduit is in the
form of a continuous tube.
Heating apparatus according to the present invention
comprises a plurality of banks of tubes for parallel spaced
location in the path of a flow of heat each bank being in
intercommunication with the or each end adjacent bank by
passage means and so disposed that the bank nearest the heat
source is upstream of the heat flow and the bank remote or
remotest from the heat source is downstream of the or each
other bank, and air flow-inducing means for inducing a flow
of air into the bank or banks of tubes at the downstream end
of the heat flow, to pass the air through successive banks,
provided to the upstream bank or banks nearest the heat
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source from which the air exits into a room or other enclosed
area, the air as it enters the downstream bank or banks of
tubes being relatively cool and being gradually heated as it
passes through successive banks of tubes to exit at the
upstream bank or banks of tubes at a higher temperature.
Preferably, where more than two banks of tubes are
provided, the spacing between adjacent banks decreases
towards the downstream bank.
Preferably the banks of tubes are formed as a unit and
are located in a containment member mounted on, in the warm
gas flow path.
Preferably the air inlet or inlets to the or the most
downstream bank or banks of tubes, being operatively
connected to said air flow-inducing means, and the air outlet
or outlets from the or the most upstream bank or banks of
tubes communicate with a common room or other enclosed area
whereby cool air is withdrawn therefrom into the banks of
tubes and heated air is returned thereto.
Preferably said tubes in banks downstream of the two
most upstream banks progressively reduce in wall thickness
from two said upstream banks.
Embodiments of the present invention will now be
described, by way of example, with reference to the
accompanying drawings, in which:
Figure 1 is a front view of a convector heating
apparatus according to a first embodiment:
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Figures 2 and 3 are an exploded view of the apparatus
shown in Figure l;
Figures 4, 5 and 6 are exploded views of the apparatus
according to a further embodiment;
Figures 7, 8 and 9 are diagrammatic views showing the
flow of heat from existing heating or cooking apparatus and
the flow of air in the banks of tubes of the apparatus
according to the invention;
Figure 10 is a schematic elevation of a third
embodiment;
Figure 11 is an end elevation of Figure 10;
Figure 12 is a parallel cross section of Figure 10 to a
smaller scale;
Figure 13 is a plan view of Figure 10;
Figure 14 is a schematic elevation of part of the
apparatus shown in Figures 10 to 13;
Figure 15 is an end elevation of Figure 14;
Figures 16 and 17 show further illustrations of heat
flow past the banks of tubes and air flow in the tubes;
Figure 18 is a schematic elevation of Figures 16 and 17
illustrating a fourth embodiment of the invention;
Figure 19 is a schematic cross section of a fourth
embodiment of the invention; and
Figure 20 is a plan view of a chimney breast for
location therein of the apparatus of the fourth embodiment.
Referring firstly to Figures 1 to 6, the room air
flowing into the system to be heated is 1 and the heated air
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returning is 2. Figure 1 is an open fire burning coal, wood,
peat, gas (artificial logs or coal), and etc., with the unit
Figure 3, fitted to the top of the open surround by a
containment 19 and 20 - figure 2 as if a drawer in its slider
to a cabinet.
Figure 4 shows a unit 30 (in exploded view) fitted to
the after flue pipe 31 of a closed fire 32.
Figure 5 shows a unit 30a fitted to the after flue pipe
31a of a solid fuel, oil or gas fired cooker/boiler 32a.
Figure 6 shows a unit 30b fitted to the flue pipe 31~ in
the chi-mney breast above an open fire 32b.
Other applications of the system are possible. A unit
may be above a ceiling mounted radiant gas heater in a
factory or warehouse. A unit with the inlet 1 and the outlet
2 on the opposite side of the wall to the heat source - e.g.
in Figure 6, and the inlet 1 and the outlet 2 may be on
opposite sides of the wall to each other, e.g. where emission
is required in an adjoining room or hallway or into an
adjacent cupboard for use as an airing cupboard. A unit may
or may not have a supply of ducted fresh air from the
exterior supplied to the inlet 1 and a unit may or may not
have air from outlet 2 ducted away to some distant use. All
applications of the system dependant on the requirements of
the user.
The working principles of the system are shown from
Figure 7 and Figure 8 which show banks of tubes A, B, C, D,
E, F, through which may be forced air say from the room. The
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flow of the air through the unit is in the form of from the
room l through the upper banks of tubes 6 down through the
communicating chamber 7 and back along the lower banks of
tubes 8 and return to the room 2. 25 is a separating
membrane. Flue gases from the heat source (fire etc.) rise
up through the array of tubes at Fl and exit at F2. As the
flue gases travel through the banks of tubes they heat up
these tubes which in turn pass their heat on to the air
passing through the tubes, Figure 9.
The passage of air through the tubes is in overall
effect in reverse order to that of the passage of the flue
gases. Cool room air entering the system meets cooled flue
gases leaving the system in the upper banks of tubes. This
room air is gradually heated as it passes through the system,
the reverse being the case for the flue gases, and meets the
hotter flue gases entering the system in the lower banks of
tubes as it - the room air - then leaves this harmonious
system.
Figures 10, 11, 12 and 13 depict a unit in schematic
elevation, end view, partial cross section and plan view,
which unit may be fitted to the upper part of the opening to
an open fire (as depicted in Figures 1 and 3) with the
containment unit depicted in Figure 14 and 15 (as depicted in
Figure 2). Air is shown entering from the room 1 through a
probable filter 3 and into the unit through the fan or fans
4, along a communication duct 5 and into the banks of tubes 6
(Figure 12, one tube drawn for clarity) and into the
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communicating duct 7 and down and back along the banks of
tubes 8 (Figure 12, one tube drawn for clarity) and exiting
into the room 2.
In the typical system with banks of tubes A, B, C, D, E,
F, there may be a unit spacing horizontally between tubes of
d for diameter, and a spacing between F and E which is less
than the spacing between E and D which is less than the
spacing between D and C which is less than the spacing
between C and B which is less than the spacing between B and
A. The net effect of this is that the spacing X between
tubes from one bank to another and through which passes flue
gases from Fl to F2, this spacing X is gradually reduced as
the flue gases approach the upper banks of tubes. The flue
gases enter the system Fl and pass through the spacing X
between banks B and A and heat is given up to the tubes
contacted (Figure 9). The flue gases - now reduced in
temperature - travel on to spacing X between banks C and B
which is smaller than that at B and A and which squeezes the
flue gases and increases the flue gas pressure at this point,
above that which it would have been had the flue gases met a
spacing X between banks C and B the same as the spacing X
between banks B and A. From gas law P.V/T is a constant this
increase in flue gas pressure has the effect of raising the
flue gas temperature as it passes through spacing X, and by
the raising of the flue gas temperature at that point
effecting an increase in the heat exchange between the flue
gases flowing round the tubes and the air flowing through the
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tubes. As the volume of flue gases remains a constant the
flue velocity through spacing X is thereby increased. This
process is repeated again and again through each spacing X at
each juncture of banks of tubes until the flue gases leave
the system F2 much reduced in temperature, and more so -
reduced in temperature - than had the flue gases merely
passed through a system with the spacing X a constant, and
with this overall effective throat system having increased
flue velocity to such an extent as to negate the possibility
of back puff into the heat source.
The gauge thickness of the tube wall (Figure 9) 26, in
the two lower banks A and B are of equal gauge and of such
thickness as to minimize their destruction from heat contact.
The system may be further enhanced by the tubes in the upper
banks above A and B being constructed of a gauge wall
thickness lighter than that of tubes A and B and reducing in
gauge wall thickness to the lightest being in the uppermost
bank. This would have the effect of maximizing the rate of
transfer of heat to the room air passing through the tubes
which room air is quenching the inner wall of the tube of the
heat conducted through the tube wall thickness. The net
effect of this being maximum heat gain in the room air and
maximum heat loss in the flow gases, i.e. maximum efficiency
in the system.
A unit may comprise any number of tubes from two upwards
depending on the system required for a particular
application.
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Figures 16 and 17 are further interpretations of the
previously stated system whereby flue gases enter at Fl and
exit at F2 through a greater number of tubes than depicted in
Figure 7, with room air entering at 1 and flowing through
tubes 6 into and down communicating duct 7 and through tubes
8 and down communicating duct 9 and through tubes 10 and down
communicating duct 11 and through tubes 12 and exiting into
the room 2. Figure 18 is a schematic elevation of Figures 16
and 17 with flue gases entering Fl and exiting F2 with room
air entering at 1 and exiting at 2, for a possible
installation to a chimney breast as depicted in Figure 6 with
a plan view of the containment depicted in Figure 20, as 19,
having flange 20 for bolting the unit in a gas proof seal,
with the unit taking heat from the gases in a standard wall
flue 21. Further adaptations of this unit are as previously
stated - into an airing cupboard and/or another room and etc.
Figure 19 is a schematic cross section of a possible
system to a boiler or cooker or free standing heater as
depicted in Figure 4 and 5 with further banks of tubes to
previously stated, - through tubes 12 - and down
communicating duct 13 and through tubes 14 and down
communicating duct 15 and through tubes 16 and exiting into
the room 2. The containment here is an open sided box 17
with flange 20 for gas proof seal and flue connector 18 at
either end of the box for connection to after flue pipe of
the heat source.
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A further adaptation may be as in Figure 1 where the
fans housings 22 may be fitted at the bottoms of legs - as
communicating ducts, vertically to and with duct 5,
immediately in front of 23 - and thereby allowing the open
fire to be increased in size forward of its original surround
23 and with a larger grate fitted forward of the original at
24. The unit is removable from its containment structure
thereby providing accessibility for the cleaning of the flue
and also the unit itself which may be immersed, e.g. in a
bath of liquids capable of dissolving any solid matter
adhering to the unit. The unit could be constructed of
materials such as stainless steel for appearance and freedom
of maintenance and, e.g. zinc galvanized or electroplated
steel tubes etc, and which unit by its removability may be
maintained by redipping etc, if required.
Central heating is generally represented by radiators
supplied with hot water from a boiler system through pipes,
and over which radiators - should be referred to as
convectors as radiation does not take place without a 200C
temperature difference between the radiator and the radiated
- flows room air convecting away the heat to room furniture
and etc, and generally raising room temperature.
With the unit fitted to an ordinary open fire, central
heating is achieved without the cost and space of an
installation of boiler, pipes or radiators. Air flowing
through the unit at temperatures well in excess of 100C from
a fan rated at say 100 CFM (cubic feet per minute) will be
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taken through or under doors, through Building Regulation
required room ventilators and/or by other means - as depicted
- to all parts of a stAn~rd sized home, and in a short space
of time drastically improve the temperature of that home.
e.g. providing forced air convection from an open fire
with 100 CFM air at 100C to a 1200 sq ft home with an
8 ft stud height could increase the average air
temperature to 25C (77F) from 0C in
100C X 100 CF per Min X 60 Min/Hr
25C 1200 X 8 CG
Given no losses, = 0.4 Hrs. / 24 Mins.
The cost of running a 100 CFM fan is 1 unit of
electricity (6.38 pence) per 40 Hrs, with a life expectancy
lS of the fan between 25,000 - 30,000 Hrs (1250 days) continuous running.
The apparatus as herein before described provides
filtered particle free air and heated (depending on the fire
built up) to temperatures well in excess of 100C, which
intensely heated air within the unit provides a bacterium and
virus destruct - the vast majority of these being destroyed
at 121C - environment, further benefiting the interior
environment of the home or workplace in providing all round
warmth from an open fire - whereas without the apparatus ones
front was warm and ones back was cold - and in providing a
dehumidified (condensation loss), and well ventilated
atmosphere.
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